Purpose: To describe the phenotype and clinical course of patients with RPGR-associated retinal dystrophies, and to identify genotype-phenotype correlations.
Methods: A multicenter medical records review of 74 male patients with RPGR-associated retinal dystrophies.
Results: Patients had retinitis pigmentosa (RP; n = 52; 70%), cone dystrophy (COD; n = 5; 7%), or cone-rod dystrophy (CORD; n = 17; 23%). The median follow-up time was 11.6 years (range 0-57.1). The median age at symptom onset was 5.0 years (range 0-14 years) for patients with RP and 23.0 years (range 0-60 years) for patients with COD/CORD. The probability of being blind (best-corrected visual acuity <0.05) at the age of 40 was 20% and 55% in patients with RP and COD/CORD, respectively. RPGR-ORF15 mutations were associated with high myopia (P = 0.01), which led to a faster best-corrected visual acuity decline in patients with RP (P < 0.001) and COD/CORD (P = 0.03). Patients with RP with RPGR-ORF15 mutations had a faster visual field decline (P = 0.01) and thinner central retina (P = 0.03) than patients with mutations in exon 1 to 14.
Conclusion: Based on best-corrected visual acuity survival probabilities, the intervention window for gene therapy for RPGR-associated retinal dystrophies is relatively broad in patients with RP. RPGR-ORF15 mutations were associated with COD/CORD and with a more severe phenotype in RP. High myopia is a risk factor for faster best-corrected visual acuity decline.